The saturation current Isat of a photodiode is determined by its open circuit voltage VOC and its serial resistance RS following the formula: Isat = VOC / RS A typical value (SiC photodiode) for VOC is 2.0 V and for RS = 5 Ohm. This calculates: Isat = 2.0 V / 5 Ohm = 0.4 A = 400 mA. The saturation radiant intensity z calculates by the below formula: z = Isat / (S * A) Where S is the radiant sensitivity of a photodiode and A is the active area. A typical value for S is 0.13 A/W and A = 0.06 mm2 (valid for SG01S). This calculates: zsat = 0.4 A / (0.130 A/W * 6 * 10-8 m2 ) = 51.28 MW/m2 = 5.13 kW/cm2

What are typical rise and fall time of different UV photodiodes?

Capacitance C

tr = 2PiRC(R = 50 Ohm)

SG01S-18

15 pF

4.7 ns

SG01M-18

50 pF

15.7 ns

SG01L-5

250 pF

78.5 ns

Is your UVC photodiode compliant to DVGW W294 (2006)?

Yes, f1,Z is smaller than 0.25.

What is the lowest pressure that the photodiode can withstand?

Our UV photodiodes are hermetically sealed and can be used under vaccum, theoretically down to 0 Pa.

When is a filtered UV photodiode needed?

Our four filtered versions of the UV photodiode lead to a tighter sensitivity range.

AMPLIFIED UV PHOTODIODES (TOCON series)

What is the maximum signal output of a TOCON?

The theoretical maximum signal output is always a little less (approx. 5%) than the supply voltage.

Do I need an external amplifier?

No, no additional amplifier is required.

How can I use my TOCON?

Please use a standard voltmeter to read out the signal. Caution! Wrong wiring of power supply can lead to immediate destruction of the device. Please refer to our application note delivered with the device.

What about the TOCON scatter?

A TOCON is a sophisticated product where a lot of different components create the TOCONs function. All of these components properties, e.g. the efficiency of the UV-sensing SiC chip or the gain resistors value scatter within a certain range. This results in the TOCONs total scatter of +-20%. per class and the availability of a number of classes for each TOCON type. This means, if you buy a certain quantity of TOCONs it could happen that one TOCON e.g. outputs a voltage of 1000 mV at a certain radiation. The less sensitive TOCON within the batch may output 1000 mV minus 20% = 800 mV and the most sensitive TOCON may output 1200 mV. In most cases the scatter does not cause problems if suited analogue or digital output voltage analysing components are used.

However, one very important point needs to be considered: The TOCON must never saturate while illuminated with UV radiation. Saturation means that the TOCON’s output voltage Vout equals to the power supply voltage Vin. Saturation will not damage the TOCON but means the output voltage is no longer proportional to the radiation to be measured.

This information is quite important for developers who purchase a certain sample quantity or just one TOCON and consider to order a volume quantity. To make sure that not a single TOCON of this volume quantity will saturate in use you should make sure that the sample(s) do not output a voltage higher than 50% of the input voltage while illuminated with the maximum radiation to be measured (e.g. the radiation of a new lamp). If Vout is higher than half of Vin one may try to increase the distance to the UV source or to purchase a less sensitive TOCON (see table below).

This +-20% scatter per class is a default value, and you should prepare your surrounding circuitry to handle TOCONs of several classes. If this causes problems, please contact us. By means of binning processes we feel able to reduce the scatter of the batch. However, please consider that also a reduced scatter still requires an individual calibration of each TOCON. Thus, usually scatter reduction does not create a technical benefit.

What is the output pin impedance (or the drive capability) of the TOCON sensor?

The TOCON can drive resistive loads as low as 2 kOhms, but we recommend not to stress this limit unnecessarily. In normal environments an input impedance of >= 100 kOhm is recommended for the readout circuitry. In very harsh (EMI/EMC/noisy) surroundings impedances of >= 10 kOhm can be considered taking into account a slight reduction in output swing.

The TOCON is stable for capacitive loads up to 30 pF under all circumstances. If more capacitive loading can not be avoided a series resistor of 10 Ohms … 100 Ohms may be required to ensure stability up to few hundred nF.

Is the TOCON calibrated?

No, the TOCON is not calibrated. If required, the sglux calibration laboratory offers an individual calibration service including a calibration certificate. This document assigns the voltage output of one specific TOCON to the irradiation of a specific UV radiation source.

As-delivered the TOCON is sensitive in the specified range. Example: A TOCON_ABC6 is sensitive between 180 nW/cm² and 1.8 mW/cm². This means that the TOCON will saturate (output voltage = input voltage) at approx. 1.8 mW/cm². At the lower end a radiation of 180 nW/cm² will still output a couple of mV. While selecting a TOCON, the most important thing to consider is to not illuminate the TOCON until saturation level. A saturation will not damage the TOCON but likely the voltage output will no longer be linear to the radiation input because any increase of radiation below the saturation point will not further increase the output voltage.

UV SENSORS

Is the probe calibrated?

No, the probe is not calibrated. If required, the sglux calibration laboratory offers an individual calibration service including a calibration certificate. This document assigns the voltage output or the current value of one specific probe to the irradiation of a specific UV radiation source. As-delivered the probe is sensitive in the specified range. Please find further details at the sglux website’s calibration section.

Do you offer a UV sensor for outdoor measurements?

We can offer our UV-Cosine sensor for outdoor measurements. The housing is waterproof IP68 at window side, stain repellent and on request submersible.

Will the DigiLog2 software also show the measured temperature of the digital UV sensor?

Yes, temperature and UV signal is read and stored.

Is it possible to simultaneously log the UV signal and the temperature?

Yes, this works.

What does „temperature compensation“ mean?

A numerical temperature compensation (compensation signal change with temperature) is possible, but not enabled. This would only be relevant for temperatures above 55°C.

UV RADIOMETER

What is the maximum logging rate of the UVTOUCH?

13.75 Hz is intrinsic acquisition frequency of the sensors. Setting a lower rate for data logging (like 1Hz) is not a problem. The logging rate can easily be changed by the user.

Is it possible to read out the UVTOUCH via computer permanently?

The measurement data is stored inside the handheld unit. To read out the data please use the USB stick. Permanent read out via PC is not possible. Please use our DIGIBOX.

Why does the UVTOUCH show higher temperatures than room temperature is measured?

The temperature indicated by the UVTOUCH is the internal temperature of the Sensor. Due to heat generation (self heating) of the PCB the temperature is always a little above the ambient temperature. This temperature is mainly used for being able to exclude destructive temperatures above 85°C.

DATALOGGER, DISPLAYS and CONTROLLER

By default, the units input terminals are NIST traceable calibrated looking at the displayed voltage (Sensor connected) and current (Photodiode connected). If the Sensor Monitor is delivered in a bundle with an UV sensor, the Sensor Monitor will come calibrated. A calibration certificate is available on demand.

Do you offer a waterproof datalogger?

Our UVMICROLOG can be configured to be waterproof.

AMPLIFIER BOARDS

What is the power input of a Multiboard?

The current consumption of a Multiboard is between 4 mA and 20 mA, depending on the amount and type of operating voltage (uni / bipolar) as well as the load at the output (multimeter = no load).